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Hi there! Sam from Moz's Help Team here! Yes, you can indeed add Page Authority as a module - however, you will only be able to do this on a root domain level. When in the Custom Reports area > Add Modules, head to the Links module and then 'Inbound Links'. You can then add the first module that appears - for your own site, as well as your competitors. If you're running into trouble finding this, just shoot us an email at help@moz.com and we'll be happy to assist!